This invention relates to an improved transformer, and particularly to a ring core transformer which has a plurality of sets of output power supply terminals with different output voltages and an improved insulated frame to mount the main body.
Generally, a transformer is an electrical apparatus which couples an alternating-current (ac) electric voltage/current at its primary source to a plurality of secondary voltage/current through a magnetic flux coupling. The principle of a transformer is to utilize the function of electromagnetic induction, which is excited the primary winding and induces the secondary windings for various voltages. The core of a transformer which provides an enclosed flux loop path is substantially made of multiple layer laminated silicon steel sheets so that the eddy currents can be minimized. The conventional magnetic core of a transformer adopts an EI type or EE type core. It has shortages of higher power consumption and therefore it is less efficient.
Recently, a ring-core transformer is developed. Although it brings better efficiency in power transformation, several defects still exist such as limitation of the number of output terminals and destruction of the insulation between terminals. Referring to FIG. 1, a perspective view of a conventional ring-core transformer is shown. Referring to FIG. 2, a secional view of a conventional ring-core transformer is shown. This conventional ring core transformer 1 comprises a ring core 11 which is usually made by silicon steel sheets, two coil formers 12 surrounding the core 11, primary/secondary windings 13 attached to said coil formers 12, several pairs of output terminals 14, insulating spacers 15 usually made of insulating papers which are distributed between the layers of terminals 14, and a metal frame 16. Each output terminal 14 leading out from the windings 13 has a central electric wire core 131 and is protected by an insulating sleeve 132. Usually, all the secondary output terminals 14 are disposed within the inter spaced gaps 17 formed between the coils 13. By means of the insulating spacers 15, sets of output terminals 14 of the windings 13 are superimposed on one another to save the space.
As previously described, although the power loss of the conventional transformer has been reduced, some defects still remain with the ring-core transformer.
(a) The output terminals 14 from the winding must be insulated by means of insulating sleeves 132 or insulation spacers 15. Moreover, the insulation on the outer surface of each wire core 131 must be pared out prior to the connection of the output terminals 14 to an electric appliance or circuit. It is also still necessary to insulate the connection by applying suitable insulating material. Therefore, in a conventional ring-core transformer is complicated and troublesome, the manufacturing cost on workman hour is high and the insulation arrangement is not economical.
(b) The number of the output terminals 14 leading out from the winding 13 are limited because the spaced gap 17 between the coils 13 is relatively restricted. As shown in FIG. 2, the spaced gap 17 allows only about four pairs of output terminals to fit in. It causes the possible output voltage values to be greatly limited, and requires the use of more transformers in a power supply system.
(c) The conventional ring core transformer is unable to be used on a printed-circuit board (PCB).
Therefore, an attempt has been made to use an improved ring-core transformer, according to this invention, to provide relatively more flexible output terminal pairs and better insulation, especially at the output terminal which leads from the windings of the transformer. Thus, a transformer of this invention not only overcomes the defects of the prior art, but also increases the lifetime and reduces the manufacturing cost thereof.